"Kiln" is a term of art which designates a type of oven used for firing ceramic wares. A hobbyist kiln, as used herein, refers to a kiln designed for use in a household which is generally smaller and constructed much more cheaply than its commercial counterpart.
In either a hobbyist or commercial kiln, ceramic material such as any member of the class of materials commonly designated as "clay", is wetted into a plastic mass and preshaped prior to being dried and then fired in the kiln into a permanently rigidized or sintered structure. The fired object is usually somewhat smaller than its unfired counterpart resulting in a product of increased strength and density.
During the firing process, a wide range of potentially hazardous chemicals are emitted from the fired object depending upon the particular clay composition utilized. At relatively low temperatures various organic compounds are emitted from the heated clay in gaseous form. More particularly, depending upon the composition of the clay material, gases containing arsenic and formaldehyde are generated at such low temperatures. At higher temperatures, metallic based gases are emitted. Additionally, for example, if a gold glaze is placed on the fired object, noxious gases are emitted at a relatively high temperature originating from the compound within which the gold particles are suspended.
Commercial kilns are typically operated to vent emitted gases out of the area in which the kilns are located. These commercial kilns are typically gas fired. In such kilns, emitted gases are oxidized to such an extent that hazardous chemicals are present at a relatively low concentration.
Hobbyist kilns are typically electrically fired. In such kilns, oxidation of emitted hazardous gases does not takes place. Additionally, operators of such hobbyist kilns are often not well informed as to the need to properly vent the kiln exhaust. Accordingly, a greater potential danger exists for the hobbyist kiln operator to be exposed to a dangerously high concentration of hazardous gas than a typical commercial kiln operator.
The exemplary embodiment of the present invention eliminates (or dramatically reduces) the contaminating components in the kiln exhaust gas by enclosing the kiln gas venting channel within the disclosed contaminant eliminator system. This system includes a heating element which is disposed adjacent to the gas venting channel. The heating element is controlled to heat the kiln exhaust gas to a temperature (e.g., 1800.degree. ) at which many of the contaminating gases change to a less harmful state. The heated exhaust gas is directed along a winding cooling path where metallic particles in the contaminated exhaust gas compounds are plated on relatively cold condensing plates. The cooled exhaust gas is then filtered to trap substantially all remaining airborne metallic or other contaminating particles.
Although the exemplary embodiment of the present invention is directed to eliminating emitted hazardous exhaust gases from kilns, the present invention may be advantageously applied to contaminating gas elimination from the exhaust of a potentially wide range of chemical process confining enclosures. For example, the present invention in addition to electric and gas kiln applications, may be advantageously used in conjunction with incinerators, furnaces, chemical process exhaust smoke stacks and other applications.